If it is hosted on dreamhost, and your account with them is still in good standing, then you can access your old data still (files will be available under your home directory in a folder using the domain of the site in question, and the databases will still be saved on the server)

If you simply had a domain redirect to blogspot, then we cannot help you, as Dreamhost is not involved at all. You’d have to reach out to Google, as they own and host Blogspot.